1. Field of the Invention
The present invention relates to a projection optical apparatus for projecting and exposing the pattern of a first object on a second object and, more particularly, to a method of adjusting the projection optical apparatus.
2. Related Background Art
A projection optical system used in an exposure apparatus that prints a precision circuit pattern on a substrate (wafer, plate, or the like) coated with a photosensitive material requires very high optical performance. For this purpose, optical members used in the projection optical system are manufactured with an ultimately high manufacturing precision.
When manufactured optical members are combined to assemble a projection optical system, very fine adjustment is performed such as adjusting the distances between the respective optical members by changing the thicknesses of washers between lens barrels holding the respective optical members, tilting the optical members (rotating the optical members about, as an axis, a direction perpendicular to the optical axis), or shifting the optical members (moving the optical members in a direction perpendicular to the optical axis), while actually measuring the aberration of the projection optical system. This adjustment minimizes degradation in optical performance which is caused by the manufacturing error of the optical members or which occurs during assembly of the optical members.
According to the present invention, there is provided a manufacturing method of a projection exposure apparatus, and the projection exposure apparatus made by that method. The method includes a first step of providing a projection optical system for forming an image of a pattern on a mask onto a substrate; a second step of providing a correction optical member made of silica glass; a third step of measuring an aberration which includes a random aberration component of the projection optical system; a fourth step of machining the correction optical member so as to correct residual aberration of the projection optical system, and a fifth step of placing the correction optical member in an optical path between the mask and the substrate, irrespective of the mask.
The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.